/**
 * Created by Administrator on 2016/4/20.
 */
function base64_decode(str) {
  var c1, c2, c3, c4;
  var base64DecodeChars = new Array(-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57,
    58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6,
    7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
    25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36,
    37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1
  );
  //    console.log("yyy:"+str);
  var i = 0,
    len = str.length,
    string = '';

  while (i < len) {
    do {
      c1 = base64DecodeChars[str.charCodeAt(i++) & 0xff]
    } while (
      i < len && c1 == -1
    );

    if (c1 == -1) break;

    do {
      c2 = base64DecodeChars[str.charCodeAt(i++) & 0xff]
    } while (
      i < len && c2 == -1
    );

    if (c2 == -1) break;

    string += String.fromCharCode((c1 << 2) | ((c2 & 0x30) >> 4));

    do {
      c3 = str.charCodeAt(i++) & 0xff;
      if (c3 == 61)
        return string;

      c3 = base64DecodeChars[c3]
    } while (
      i < len && c3 == -1
    );

    if (c3 == -1) break;

    string += String.fromCharCode(((c2 & 0XF) << 4) | ((c3 & 0x3C) >> 2));

    do {
      c4 = str.charCodeAt(i++) & 0xff;
      if (c4 == 61) return string;
      c4 = base64DecodeChars[c4]
    } while (
      i < len && c4 == -1
    );

    if (c4 == -1) break;

    string += String.fromCharCode(((c3 & 0x03) << 6) | c4)
  }
  return string;
};


function utf16ToUtf8(s) {
  if (!s) {
    return;
  }

  var i, code, ret = [],
    len = s.length;
  for (i = 0; i < len; i++) {
    code = s.charCodeAt(i);
    if (code > 0x0 && code <= 0x7f) {
      //单字节
      //UTF-16 0000 - 007F
      //UTF-8  0xxxxxxx
      ret.push(s.charAt(i));
    } else if (code >= 0x80 && code <= 0x7ff) {
      //双字节
      //UTF-16 0080 - 07FF
      //UTF-8  110xxxxx 10xxxxxx
      ret.push(
        //110xxxxx
        String.fromCharCode(0xc0 | ((code >> 6) & 0x1f)),
        //10xxxxxx
        String.fromCharCode(0x80 | (code & 0x3f))
      );
    } else if (code >= 0x800 && code <= 0xffff) {
      //三字节
      //UTF-16 0800 - FFFF
      //UTF-8  1110xxxx 10xxxxxx 10xxxxxx
      ret.push(
        //1110xxxx
        String.fromCharCode(0xe0 | ((code >> 12) & 0xf)),
        //10xxxxxx
        String.fromCharCode(0x80 | ((code >> 6) & 0x3f)),
        //10xxxxxx
        String.fromCharCode(0x80 | (code & 0x3f))
      );
    }
  }

  return ret.join('');
}

function utf8ToUtf16(s) {
  if (!s) {
    return;
  }

  var i, codes, bytes, ret = [],
    len = s.length;
  for (i = 0; i < len; i++) {
    codes = [];
    codes.push(s.charCodeAt(i));
    if (((codes[0] >> 7) & 0xff) == 0x0) {
      //单字节  0xxxxxxx
      ret.push(s.charAt(i));
    } else if (((codes[0] >> 5) & 0xff) == 0x6) {
      //双字节  110xxxxx 10xxxxxx
      codes.push(s.charCodeAt(++i));
      bytes = [];
      bytes.push(codes[0] & 0x1f);
      bytes.push(codes[1] & 0x3f);
      ret.push(String.fromCharCode((bytes[0] << 6) | bytes[1]));
    } else if (((codes[0] >> 4) & 0xff) == 0xe) {
      //三字节  1110xxxx 10xxxxxx 10xxxxxx
      codes.push(s.charCodeAt(++i));
      codes.push(s.charCodeAt(++i));
      bytes = [];
      bytes.push((codes[0] << 4) | ((codes[1] >> 2) & 0xf));
      bytes.push(((codes[1] & 0x3) << 6) | (codes[2] & 0x3f));
      ret.push(String.fromCharCode((bytes[0] << 8) | bytes[1]));
    }
  }
  return ret.join('');
}

export default {
  toUtf16(str) {
    if (str == undefined) {
      return;
    }
    var Str = base64_decode(str);
    Str = utf8ToUtf16(Str);
    return Str;
  }
}